#include <iostream>
#include <math.h>
using namespace std;

class Solution 
{
public:
    double tmp = 0;
    double myPow(double x, int n) 
    {
        if(x == 1) return 1;
        return n < 0 ? pow(1/x, -(long long)n) : pow(x, n);
    }
    double pow(double x, int n)
    {
        if(n == 0) return 1.0;
        tmp = pow(x, n / 2);
        return n % 2 == 0 ? tmp * tmp : tmp * tmp * x;
    }
};

void Test01()
{
    Solution s;
    double ans = s.myPow(0.5, 200000000);
    cout << ans << endl;
}

int main()
{
    Test01();

	return 0;
}